In reaction, close friends of Diana and other admirers have sharp words to criticize the move as exploitative.

Rosa Monckton, for many years one of Diana's closest confidantes, said: "I really don't have any words to describe how I feel about this cynical and shameless attempt to publicize a film that should never have been made."

She continues: "To have made a film so speculative and as this is disgusting enough, but to then advertise it on the spot at which she died is despicable. … It is a terrible intrusion into her memory, not to mention the lives of her sons, whose feelings are often forgotten in these stories. I would expect them to take it down right now."

The 6'x4' poster over the Alma underpass stands only a few feet away from the gold-leafed Flame of Liberty, which became Diana's unofficial memorial following her death.

There was no immediate comment from the makers or distributors of the film. A spokesman for Paris City Hall said that the posters were on display "all over" Paris, and that the one above the Alma tunnel was "one of many."

He added that all the posters were displayed legally.

Diana remains hugely popular in Paris, where she is still referred to as "Lady D," and many of those paying their respects on this anniversary added their own disapproval of the poster.

"It couldn't be more disrespectful," said Sarah Hume, a 19-year-old American student. "This is where Diana died, and yet the film producers are trying to promote their film here. They should be ashamed."

"Her memory should not be besmirched in this manner,' said Celine Durant, 38, a local shop worker who remembers "Lady D.'s terrible end – the place where it happened should not be marked with a film advertisement."

The movie, loosely based on Diana's romance with Dr. Hasnat Khan (which ended in 1997, just before she died alongside another boyfriend, Dodi Al-Fayed), has already been widely panned in Britain and is now opening in Paris to equally appalling reviews.

Critic Jérôme Garcin, of the Nouvel Observateur, said of the film that it was impossible to imagine anything "more stupid, more ugly."